US20050267401A1 - Safety interlock system for an enteral feeding pump - Google Patents

Abstract

A safety interlock system for a flow control apparatus is disclosed that permits operation when a magnet-less administration feeding set is properly mounted to recess formed along the housing of the flow control apparatus. The administration feeding set comprises flexible patient tubing having a support member at one end and a mounting member including a magnetically-susceptible metallic component at the other end thereof. A sensing arrangement is provided by the flow control apparatus for sensing the proper engagement of the metallic component to the recess of the flow control apparatus. A control means permits operation of the flow control apparatus when the metallic member is properly engaged to recess, while terminating operation when the metallic member is improperly engaged to recess.

Description

RELATED APPLICATIONS
• This application is a 371 National Stage Application for International Application PCT/US03/10713, filed Apr. 7, 2003, which claims priority from U.S. Provisional Patent Application No. 60/413,710, filed Sep. 26, 2002.
BACKGROUND OF THE INVENTION
• 1. Field of the Invention
• The present invention relates to a safety interlock system, and more particularly to a safety interlock system for a flow control apparatus. More specifically, the present invention relates to a safety interlock system using a magnet-less administration feeding set with an enteral feeding pump.
• 2. Prior Art
• Enteral feeding systems are frequently used for patients who are unable to take nutrition alone and require some type of feeding system to provide nutrition through a gastrointestinal tract of a patient, such as the stomach. Typically, an enteral feeding system comprises a disposable administration feeding set in conjunction with a flow control apparatus, such as a pump, for supplying fluid to a patient at a controlled delivery rate. The administration feeding set of the prior art includes an inlet tube in communication with a source of fluid at one end and a drip chamber which is arranged to be mounted along a first recess on the pump at the other end, a mounting member for mounting the administration feeding set to a second recess on the pump, and a pump tube which connects the drip chamber to the mounting member while engaging a motor driven rotor on the pump.
• In many enteral feeding systems the engagement of the pump tube to the rotor controls the flow of fluid to the patient according to the speed of the rotor. In the event the administration feeding set is not properly mounted to the pump, an excess flow of fluid through the feeding set can occur under force of gravity which is highly undesirable. Improper mounting of the drip chamber is unlikely because of the mechanical configuration of that component and its corresponding recesses on the pump. However, improper placement of the mounting member, e.g. below, above or outside of the respective recess on the pump is more likely if the administration feeding set is improperly installed on the pump by an inexperienced operator who has not yet received proper instruction in the operation of the enteral feeding system. Instances of such improper installation of the administration feeding set have been reported.
• U.S. Pat. Nos. 4,913,703; 5,201,711; and 6,017,326 to Pasqualucci et al. disclose a safety interlock system for a flow control apparatus provided with a magnetic field source in the region of its mounting to an administration feeding set having a magnetic source, such as a magnet, incorporated into the mounting member. The flow control apparatus includes a magnetic field sensitive switching component which detects the proper placement of administration feeding set in the recess of the flow control apparatus and prevents operation of the flow control apparatus unless the mounting member of the administration feeding set is in a properly engaged position to the pump. Although the safety interlock system of Pasqualucci et al. provides an excellent means of ensuring proper engagement of the administration feeding set on the flow control apparatus, the magnet used to provide the magnetic source on the disposable administration feeding set makes it relatively expensive to manufacture.
• Therefore, there appears a need in the art for a safety interlock system that is inexpensive to manufacture. There is a further need in the art for a safety interlock system that does not require an administration feeding set having a magnet in order to ensure proper placement of the feeding set on the flow control apparatus.
OBJECTS AND SUMMARY OF THE INVENTION
• Accordingly, the primary object of the present invention is to provide a safety interlock system for an enteral feeding system that ensures the proper placement of the administration feeding set on a flow control apparatus.
• Another object of the present invention is to provide an administration feeding set for a safety interlock system having no magnetic source, such as a magnet.
• A further object of the present invention is to provide an administration feeding set for a safety interlock system that is inexpensive to manufacture.
• Another further object of the present invention is to provide a safety interlock system having a sensor arrangement inside the flow control apparatus for detection of a magnetically-susceptible metallic component on the administration feeding set.
• Yet a further object of the present invention is to provide an administration feeding set for a safety interlock system having a sensor arrangement inside the flow control apparatus that senses a variation in the magnetic field when the feeding set is properly installed.
• These and other objects of the present invention are realized in the preferred embodiment of the present invention, described by way of example and not by way of limitation, which provides for a magnet-less administration feeding set for a safety interlock system used in a flow control apparatus.
• In brief summary, the present invention overcomes and substantially alleviates the deficiencies in the prior art by providing a safety interlock system for an enteral feeding system comprising an administration feeding set adapted for operative engagement with a flow control apparatus for delivery of fluid at a controlled rate to a patient.
• According to one aspect of the present invention there is provided a method for preventing improper system operation which comprises the steps of providing a sensor arrangement inside the flow control apparatus which is operatively associated with a switching component that places the flow control apparatus in a first electrical state when the administration feeding set is properly mounted to the flow control apparatus and a second electrical state when the administration feeding set is not properly mounted to the flow control apparatus. In operation, the flow control apparatus is enabled in response to the first electrical state and disabled in response to the second electrical state. The second electrical state will prevent the flow control apparatus from operating while causing an alarm to be activated when operation of the flow control apparatus is attempted.
• In accordance with another aspect of the present invention there is provided a flow control apparatus which is arranged to receive a corresponding administration feeding set. The switching component is responsive to the proper mounting of the administration feeding set and is provided with a control means responsive to the switching component for permitting operation of the flow control apparatus only when the switching component detects proper mounting of the administration feeding set. Preferably, the switching component is operatively associated with a sensor arrangement comprising a Hall-effect sensor and magnet reconfigured to be back-biased to enable detection of a magnetically-susceptible metallic component on the administration feeding set by the switching component when the feeding set is properly mounted to the flow control apparatus.
• In accordance with another aspect of the present invention there is provided a disposable administration feeding set adapted to be operatively connected to a flow control apparatus for controlled delivery of fluid to a patient. The flow control apparatus includes a switching component for interrupting the operation thereof when the administration feeding set is improperly engaged to the flow control apparatus, wherein the administration feeding set includes a magnetically-susceptible metallic component for detection by the sensor arrangement which activates the switching component upon improper operative engagement of the tubing and prevents operation of the flow control apparatus.
• In accordance with another aspect of the present invention there is also provided a disposable administration feeding set including flexible tubing adapted to be operatively connected to the flow control apparatus, wherein the administration feeding set includes a magnetically-susceptible metallic component for detection by the sensor arrangement which activates the switching component to permit flow control apparatus operation only upon proper operative engagement of the feeding set thereto.
• Additional objects, advantages and novel features of the invention will be set forth in the description which follows, and will become apparent to those skilled in the art upon examination of the following more detailed description and drawings in which like elements of the invention are similarly numbered throughout.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a perspective view of the enteral feeding system according to the present invention;
• FIG. 2 is a perspective view of the enteral feeding system illustrating the interior of the flow control apparatus according to the present invention;
• FIG. 3A is a perspective view illustrating the internal arrangement of the safety interlock system according to the present invention;
• FIGS. 3B-3D are perspective views illustrating the improper placement of the safety interlock system according to the present invention;
• FIG. 4 is a schematic diagram illustrating the electrical connection of a switching component according to the present invention;
• FIG. 4ais a flow chart illustrating the flow logic of the microcontroller according to the present invention;
• FIG. 5 is a top view of a mounting member according to the present invention;
• FIG. 6 is a cross-sectional view of the mounting member taken along lines5-5 ofFIG. 4 according to the present invention;
• FIG. 7 is a cross-sectional view of a safety interlock system taken along lines6-6 ofFIG. 1 according to the present invention;
• FIG. 8 is plan view of a magnetically-susceptible metallic component according to the present invention;
• FIG. 9 is a cross-sectional view of the magnetically-susceptible metallic component taken along lines8-8 ofFIG. 7 according to the present invention;
• FIG. 10 is a simplified block diagram showing a preferred embodiment of the safety interlock system using a back biased sensor arrangement according to the present invention;
• FIG. 10A is a simplified block diagram of an alternative arrangement shown inFIG. 10 of the safety interlock system according to the present invention.
• FIG. 11 is a simplified block diagram showing an alternative embodiment of the safety interlock system using a resonant coil arrangement according to the present invention;
• FIG. 11A is a schematic diagram showing of the alternative embodiment shown inFIG. 11 of the safety interlock system according to the present invention;
• FIG. 12 is a schematic diagram showing another alternative embodiment of the safety interlock system using a balanced coil arrangement according to the present invention; and
• FIG. 13 is a schematic diagram showing another alternative embodiment of the safety interlock system using a differential active coil arrangement according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
• Referring to the drawings, the preferred embodiment of the safety interlock system according to the present invention is illustrated and generally indicated as11 inFIG. 1.Safety interlock system11 is preferably used with aflow control apparatus12, such as a peristaltic pump or other suitable infusion device, of anenteral feeding system10 for providing fluid to a patient's gastrointestinal tract (not shown) at a controlled rate of delivery. An administration feeding set14 is operatively engaged with aflow control apparatus12 for transporting fluid through aninlet tube16 connected to a source of fluid (not shown) at one end and apump tube15 at the opposite end. Administration feeding set14 further includes asupport member18 attached between theinlet tube16 and thepump tube15 for direct engagement of the feeding set14 to theflow control apparatus12 as shall be explained in greater detail below. In an alternative embodiment of administration feeding set14, a drip chamber (not shown) may be substituted for thesupport member18 in order to control the flow of fluid through the feeding set14.
• Referring toFIGS. 1 and 2, flowcontrol apparatus12 comprises arotor22 driven by a motor (not shown) that rotatesrotor22 at a predetermined speed at specific time intervals between cycles ofrotor22 to control the rate of delivery of fluid through administration feeding set14. In addition, delivery of fluid may also be controlled by varying the angle of rotation ofrotor22 on each cycle. Ahousing20 encloses the motor and forms recesses28 and29 for properly mounting of administration feeding set14. As shown,pump tube15 is attached to supportmember18 at its inlet end44 and to a mountingmember30 at its outlet end46. When properly engaging the administration feeding set14 to flowcontrol apparatus12,support member18 is seated inrecess28,pump tube15 is engaged aroundrotor22, and mountingmember30 is properly mounted inrecess29.
• Referring toFIGS. 1, 5 and6, mountingmember30 is attached to the outlet end ofpump tube15 by an engagingmember35 on the bottom side ofmember30 and atube receiving member27 at the top side thereof. As further shown, a circular shaped magnetically-susceptiblemetallic component21 is disposed within mountingmember30 which surroundspump tube15. Anoutlet tube17 is attached to thetube receiving member27 for allowing fluid flow to the patient frompump tube15.
• In accordance with one aspect of the present invention,safety interlock system11 provides a means for assuring the proper placement of administration feeding set14 onflow control apparatus12, and in particular with the proper placement of thepump tube15 around therotor22 to form a peristaltic pump which provides accurate and controlled delivery rate of fluid through feeding set14.
• As illustrated inFIG. 1,support member18 is received inrecess28 and mountingmember30 is received inrecess29. When properly mounted,pump tube15, which is typically made from silicone tubing, is tightly stretched aroundrotor22 so that the points of therotor22 contact onpump tube15 and progressively close the conduit23 thereof during operation. Referring toFIG. 3A, there is shown the proper placement of the administration feeding set14 onflow control apparatus12 such that thesupport member18 is properly seated inrecess28 and mountingmember30 is mounted intorecess29.
• A person of ordinary skill in the art will appreciate that in some cases the mountingmember30 ofsafety interlock system11 may be improperly installed by inexperienced personnel so that the mountingmember30 is seated belowrecess29 as shown inFIG. 3B. This particular arrangement can be hazardous to a patient because of excess and uncontrolled flow of fluid through the administration feeding set under force of gravity, whereby fluid is delivered at a higher rate than properly specified for the patient. Another improper mounting of the administration feeding set is illustrated inFIG. 3C, wherein mountingmember30 is caught on the lip ofrecess29 and not properly seated therein. Finally, another improper mounting is shown inFIG. 3D wherein mountingmember30 is not placed completely back intorecess29, but seats on the outer edge thereof. On the other hand, experience has shown that improper placement ofdrip chamber18 itself is unlikely since it must be seated in bothrecesses26 and28 in order to be properly engaged.
• In accordance with a preferred embodiment of the present invention, asensor arrangement33 preferably comprising a back-biased sensor31 is provided insideflow control apparatus12 for detecting the proper placement of mountingmember30 inrecess29. Referring toFIGS. 5-9, themetallic component21, preferably a ferrous alloy, is used to detect the proper placement of mountingmember30 inrecess29 which is a toroidal shaped component added to mountingmember30 that surrounds the fluid passage ofpump tube15. Preferably, back-biased sensor31 is provided withinhousing20 and arranged to detect the presence of themetallic component21 when mountingmember30 is properly seated withinrecess29.FIGS. 1 and 2 show the internal arrangement ofhousing20 indicating the proper placement ofmetallic component21 against the inner walladjacent recess29. Back-biased sensor31 comprises asensor arrangement33 including a biasingmagnet36 operatively associated with a Hall-Effect or magneto-resistive sensor34, as illustrated inFIG. 10. In configuration,sensor34 is interposed betweenrecess29 and biasingmagnet36 such that the magnetic flux between themagnet36 andsensor34 is changed by the presence of themetallic component21 when the mountingmember30 is properly seated inrecess29. This change in magnetic flux caused by themetallic component21 being properly received withinrecess29 is sensed bysensor arrangement33 and a signal is communicated to a microcontroller40 (FIG. 4), or other control means, which will halt the operation offlow control apparatus12 and an alarm is sounded as shown inFIG. 4. Therefore, when the mountingmember30 is disengaged from therecess29, improperly seated therein, or themetallic component21 is displaced during operation, themetallic component21 is not sensed by thesensor arrangement33 and themicrocontroller40 terminates operation of theflow control apparatus12 and sound an alarm. This operation is illustrated inFIG. 4awherein after the operation offlow control apparatus12 is started atstep400, themicrocontroller40 determines whether the administration feeding set14, and more particularly the mountingmember30, is properly seated inrecess29. If themicrocontroller40 determines that the administration feeding set14 is properly mounted, then normal operation of theflow control apparatus12 is permitted atstep404. However, if themicrocontroller40 determines that the administration feeding set14 is improperly mounted to therecess29, then operation of theflow control apparatus12 is terminated and an alarm is sounded atstep406. After operation is terminated, the user must then re-load the administration feeding set14 to the flow control apparatus atstep408 which allows themicrocontroller40 to start operation atstep400.
• In accordance with another aspect of the present invention analternative embodiment111 of safety interlock system is contemplated. As shown inFIGS. 11 and 11A,safety interlock system111 comprises aresonant circuit154 with acoil arrangement156 which collectively act as a resonant coil arrangement or tank circuit. In configuration,coil arrangement156 is disposed along theinner housing20 offlow control apparatus12 such thatarrangement156 is directly interposed between theresonant circuit154 andmetallic component21 whencomponent21 is properly received withinrecess29. As shown inFIG. 11A,resonant circuit154 comprises acapacitor158 in parallel with aninductive coil155 which are both connected to a transistor159 through aresistor157 that produces a resonant frequency withcoil arrangement156 of:
  1/2π{square root}{square root over (LC)}
  where L is the inductance ofinductive coil155 and C is the capacitance ofcapacitor158.
• In operation, whenmetallic component21 is properly received withinrecess29, the presence ofcomponent21 changes the resonant frequency produced byresonant circuit154. The change in inductance produced ininductive coil155 in the presence ofmetallic component21 changes the resonant frequency to:
  1/2π{square root}{square root over (L₁C)}
  where L1 is the inductance ofinductive coil155 in the presence ofmetallic component21. This change in resonant frequency is detected at Vr, the voltage response of theresonant circuit154, which is then communicated tomicrocontroller40.
• In accordance with another aspect of the present invention analternative embodiment211 of safety interlock system is contemplated. Referring toFIG. 12,safety interlock system211 comprises a first inductive coil212 in parallel with a secondinductive coil214 which are both driven by adriver circuit216 connected to a power source (not shown) which collectively act as a balanced coil arrangement. First and secondinductive coils212 and214 are wound in opposing directions such that theinductive coils212 and214 produce a resonant frequency of:
• 1/2π{square root}{square root over ((L₁L₂)C)}
• where L1 and L2 are the inductance of the first and secondinductive coils212 and214, respectively. The above arrangement assumes that the first and secondinductive coils212 and214 are sufficiently spaced apart as to have negligible mutual interactions.
• In configuration, first and secondinductive coils212 and214 are arranged such thatmetallic component21 is placed directly betweeninductive coils212 and214 when properly received withinrecess29. Such placement of themetallic component21 changes the resonant frequency produced between first and secondinductive coils212 and214 by altering the coupling between the first and secondinductive coils212 and214 by reducing the sum total of L1 and L2 which can then be detected at voltage Vcc and communicated tomocrocontroller40.
• In accordance with another aspect of the present invention analternative embodiment311 of safety interlock system is contemplated. As illustrated inFIG. 13,safety interlock system311 comprises adriver circuit320 which drives a first driverinductive coil316 in series with a second driverinductive coil318 that collectively act as a differential active coil arrangement. First and second driverinductive coils316 and318 are in close proximity with a senseinductive coil314 which is operatively associated with andifferential amplifier322. In configuration,safety interlock system311 is arranged such thatmetallic component21 is placed adjacent to driverinductive coil318. The senseinductive coil314 is located between the first and second driverinductive coils316 and318. When nometallic component21 is present, there is only a small voltage, Vr, produced at the output ofdifferential amplifier322. However, in the presence of themetallic component21 withinrecess29 the inductance of second driverinductive coil318 is decreased relative to first driverinductive coil316 which unbalances thesystem311 and causes the voltage at the output ofamplifier322 to increase. This unbalancing ofsafety interlock system311 is sensed at Vr, the response voltage ofsense coil314, which is then communicated tomicrocontroller40.
• It is contemplated that thesafety interlock system11 can be used with different types of flow control apparatuses12. For example, flowcontrol apparatuses12 such as peristaltic, linear peristaltic and rotary peristaltic pumps are felt to fall within the present invention. Further, the fluid administration set14 can have a drip chamber for providing a visual indication of fluid flow, or an ultrasonic sensor arrangement, such as a piezoelectric transmitter and receiver, may be attached to theflow control apparatus12 in order to detect fluid flow in lieu of a drip chamber.
• Although particular embodiments of the invention have been shown, it is not intended that the invention be limited thereby, instead, it is intended that the present invention be limited by only the appended claims.

Claims (20)

1. An enteral feeding system comprising:

a magnet-less administration feeding set, said magnet-less administration feeding set forming a conduit adapted for fluid flow therethrough, and

a flow control apparatus operatively associated with said administration feeding set for establishing fluid flow through said conduit, said flow control apparatus further including a sensor arrangement for sensing the proper engagement of said magnet-less administration feeding set to said flow control apparatus.

2. The enteral feeding system according toclaim 1, wherein when said administration feeding set includes a metallic component, said sensor arrangement provides a means for sensing the presence of said metallic component when said administration feeding set is properly engaged to said flow control apparatus.

3. The enteral feeding system according toclaim 2, wherein said flow control apparatus further includes first and second recesses for operatively engaging said administration feeding set to said flow control apparatus.

4. The enteral feeding system according toclaim 3, wherein said administration feeding set further includes a mounting member for mounting said metallic component to said second recess.

5. The enteral feeding system according toclaim 4, wherein said administration feeding set further includes a support member, wherein said support member is adapted to be engaged within said first recess.

6. The enteral feeding system according toclaim 5, wherein said sensor arrangement comprises a magnet operatively associated with a sensor.

7. The enteral feeding system according toclaim 6, wherein magnetic flux lines present between said magnet and said metallic component change when said mounting member is properly engaged to said second recess which is sensed buy said sensor.

8. The enteral feeding system according toclaim 2, wherein said sensor arrangement comprises a back-biased sensor and magnet wherein said sensor senses the presence of said metallic component when said administration feeding set is properly engaged to said flow control apparatus by the change in magnetic flux lines between said magnet and said metallic component.

9. The enteral feeding system according toclaim 2, wherein said sensor arrangement comprises a resonant circuit with a coil arrangement which sense the presence of said metallic component when said administration feeding set is properly engaged to said flow control apparatus.

10. The enteral feeding system according toclaim 9, wherein said resonant circuit and said coil arrangement comprise a capacitor in parallel with an inductive coil which are in series with a transistor through a resistor.

11. The enteral feeding system according toclaim 2, wherein said sensor arrangement comprises a first inductive coil in parallel with a second inductive coil which sense the presence of said metallic component when said administration feeding set is properly engaged to said flow control apparatus.

12. The enteral feeding system according toclaim 2, wherein said sensor arrangement comprises a first inductive coil in series with a second inductive coil, said first and second inductive coils being in parallel with a third inductive coil which collectively sense the presence of said metallic component when said administration feeding set is properly engaged to said flow control apparatus.

13. The enteral feeding system according toclaim 12, wherein said third inductive coil is operatively associated with an amplifier, said amplifier including a voltage output that increases in the presence of said metallic component.

14. The enteral feeding system according toclaim 1, wherein said sensor arrangement is operatively associated with a microcontroller, said microcontroller permitting operation of said flow control apparatus when said administration feeding set is properly engaged to said flow control apparatus and prevents operation thereof when said administration feeding set in improperly engaged to said flow control apparatus.

15. The enteral feeding system according toclaim 1, wherein said administration feeding set is magnet-less.

16. The enteral feeding system according toclaim 2, wherein said metallic component comprises a magnetically-susceptible metallic component having a ferrous alloy.

17. An enteral feeding system comprising:

an administration feeding set, said administration feeding set forming a conduit adapted for fluid flow therethrough, said administration feeding set further including a magnetically-susceptible component, and

a flow control apparatus operatively associated with said administration feeding set for establishing fluid flow through said conduit, said flow control apparatus further including a sensor arrangement for sensing the proper engagement of said magnetically-susceptible component to said flow control apparatus.

18. A safety interlock system comprising:

an administration feeding set including a magnetically-susceptible component; and

a flow control apparatus including a sensor arrangement for sensing the presence of said magnetically-susceptible component, said flow control apparatus further including a control means for permitting operation thereof when said magnetically-susceptible component is properly engaged to said flow control apparatus and terminating operation thererof when said magnetically-susceptible component is improperly engaged to said flow control apparatus.

19. A method for safety interlock between a flow control apparatus and an administration feeding set comprising:

a) providing an administration feeding set, said administration feeding set forming a conduit for fluid flow communication therethrough, said administration feeding set further including a magnetically-susceptible component;

b) providing a flow control apparatus, said flow control apparatus comprising a control means for permitting controlled delivery of said fluid through said conduit of said administration feeding set, said flow control apparatus including a housing defining a recess and a sensor arrangement;

c) engaging said magnetically-susceptible component to said recess such that said sensor arrangement senses the presence of said magnetically-susceptible component; and

d) permitting operation of said flow control apparatus by said control means when said sensor arrangement senses the presence of said magnetically-susceptible component.

20. The method according toclaim 19, wherein said control means prevents operation of said flow control apparatus when said administration feeding set is improperly engaged to said flow control apparatus.

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